The present invention relates to the field of valves, and more particularly to valve stems and stem packings that prevent leaks around valve stems.
A problem often encountered with valves is leaks around the valve stem due to wear on the stem packing. The conventional shape of a stem packing is a cylinder with a hole through the center to receive the valve stem. A gap develops between the stem packing and the valve stem due to frictional wear. This gap allows leaks to occur. It would be desirable, therefore, to provide a valve which does not readily develop leaks between a valve stem and its stem packing.
Another problem associated with valves occurs when a retaining nut is over-tightened resulting in a stem packing being excessively compressed against the valve stem. When this occurs, the valve stem is difficult to turn because of excessive friction between the valve stem and the stem packing, and the stem packing wears prematurely because of the excessive friction. It would be desirable, therefore, to provide a valve that prevents the retaining nut from being over-tightened.
Accordingly, it is an object of the present invention to provide a valve which does not readily develop leaks between a valve stem and its stem packing.
Another object of the invention is to provide a valve that prevents a threaded retaining nut from being over-tightened.
Additional objects, advantages, and novel features of the invention will be set forth in part in the description that follows and in part will become apparent to those skilled in the art upon examination of the following or may be learned with the practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.